During chemical desensitization of GTN-containing waste streams with calcium hydroxide the epoxides glycidol and glycidyl nitrate are formed. The epoxide rings of both compounds are unstable to heat in aqueous solutions and open to form glycerol l-mononitrate and presumably glycerol. These transformations are accelerated by microbiological activity. Glycerol l- mononitrate is slowly denitrated to form glycerol. Glycidol and glycidyl nitrate cause base pair substitutions in the Ames test for mutagenicity while glycerol l-mononitrate tests negative.